1. Field of the Invention
The present invention relates to a discharge electrode and a process chamber of a dry etching facility for manufacturing semiconductor devices for uniformly forming the ion density of plasma over a wafer, and reducing the volume of the process chamber by installing a plurality of discharge openings on an electrode housing comprising the electrode, thereby uniformly forming an ion density on a wafer.
2. Background of the Related Art
A photolithography process of a semiconductor device fabrication process is performed by coating photoresist on a wafer and performing an etch process after forming a pattern.
The etch process may be a wet method using chemicals or a dry method using gas. Also, the etch process may be a whole etch, in which the entire photoresist layer is removed from the wafer, or etching may be carried out using portions of the photoresist as a mask.
The etch process is primarily a chemical reaction to which physical factors such as sputtering are added. Etching was one of the early surface treatment methods, and developed from etching silicon, etc., to selective etch technologies for an oxide silicon layer, and then to the development of etch technologies for an aluminum layer to form an electrode.
Recently, wet etch for digestion etch, eminent etch, or spray etch, etc., have been replaced by a dry etch. The dry etch process is advantageous in that it avoids treatment for waste water, instability of etch solution after preparation, difficulties with isotropic etch, and nonuniform pattern etches caused by air bubbles, etc. Dry etches are widely used and comprise, for example, gas etch, plasma etch, sputtering etch and ion beam etch.
Plasma etching is shown in FIGS. 1 and 2 using a conventional dry etch apparatus. The apparatus is constructed such that two electrodes, upper electrode 1 and lower electrode 2, are placed facing each other, and upper electrode 1 functions as a cover for the process chamber. In addition, the upper electrode 1 has a surface which is the same width or wider than the lower electrode 2. There is a wafer 5 placed between the upper electrode 1 and the lower electrode 2. High frequency power is supplied between the upper electrode 1 and the lower electrode 2. In addition, a process gas is supplied over the wafer 5 so as to perform the etch process. The reacted process gas and other by-products are discharged through a discharge pipe 4 connected to a vacuum pump (not shown). An insulator 3 is provided between the upper electrode 1 and the discharge pipe 4 to minimize the effect of high frequency power. Normally, the discharge pipe 4 is made of an insulator material.
In addition, the inlet of the discharge pipe 4 is placed lower than the wafer 5 to easily discharge any powder generated as by-products of the reaction. The discharge pipe 4 is connected to a vacuum pump, and functions to evacuate the inside of the process chamber.
However, as shown in FIGS. 1 and 2, since the discharge pipe 4 is placed adjacent to lower electrode 2 on which the wafer 5 is placed, a nonuniform ion density plasma results on the wafer 5 due to the size and location of the discharge pipe 4. Accordingly, the etch process is nonuniform. In addition, since the open discharge pipe 4 is located next to where the etch process is carried out, the volume of the process chamber is increased by the volume of the discharge pipe. In addition, this location of the discharge pipe makes the entire dry etch facility larger, which means it occupies more space in the clean room, and lowers the efficiency of the clean room, particularly in the case of large-diameter wafers.